An improved land biosphere module for use in the DCESS Earth system model (version 1.1) with application to the last glacial termination
Interactions between the land biosphere and the atmosphere play an important role for the Earth's carbon cycle and thus should be considered in studies of global carbon cycling and climate. Simple approaches are a useful first step in this direction but may not be applicable for certain clim...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-09-01
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| Series: | Geoscientific Model Development |
| Online Access: | https://www.geosci-model-dev.net/10/3481/2017/gmd-10-3481-2017.pdf |
| Summary: | Interactions between the land biosphere and the atmosphere play an important
role for the Earth's carbon cycle and thus should be considered in studies of
global carbon cycling and climate. Simple approaches are a useful first step
in this direction but may not be applicable for certain climatic conditions.
To improve the ability of the reduced-complexity Danish Center for Earth
System Science (DCESS) Earth system model DCESS to address cold climate
conditions, we reformulated the model's land biosphere module by extending it
to include three dynamically varying vegetation zones as well as a permafrost
component. The vegetation zones are formulated by emulating the behaviour of
a complex land biosphere model. We show that with the new module, the size
and timing of carbon exchanges between atmosphere and land are represented
more realistically in cooling and warming experiments. In particular, we use
the new module to address carbon cycling and climate change across the last
glacial transition. Within the constraints provided by various proxy data
records, we tune the DCESS model to a Last Glacial Maximum state and then
conduct transient sensitivity experiments across the transition under the
application of explicit transition functions for high-latitude ocean
exchange, atmospheric dust, and the land ice sheet extent. We compare
simulated time evolutions of global mean temperature, <i>p</i>CO<sub>2</sub>,
atmospheric and oceanic carbon isotopes as well as ocean dissolved oxygen
concentrations with proxy data records. In this way we estimate the
importance of different processes across the transition with emphasis on the
role of land biosphere variations and show that carbon outgassing from
permafrost and uptake of carbon by the land biosphere broadly compensate for each other during the temperature rise of the early last deglaciation. |
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| ISSN: | 1991-959X 1991-9603 |